1. Field of the Invention
The present invention relates to a broadband wireless access system.
2. Description of the Related Art
In a next generation system, i.e., a 4th Generation (4G) communication system, research and commercialization are underway to provide users with various services having a data rate of about 100 Mbps or higher. More particularly, the 4 G communication system is currently being developed to ensure mobility and Quality of Service (QoS) in a Broadband Wireless Access (BWA) communication system, such as a Wireless Local Area Network (WLAN) system and a Wireless Metropolitan Area Network (WMAN) system. A representative example of such a communication system is an Institute of Electrical and Electronics Engineers (IEEE) 802.16 communication system.
According to a service protocol based on an IEEE 802.16e/m and Worldwide Interoperability for Microwave Access (WiMAX) network location, the following procedure proceeds upon receiving a request for delivering location information of a Mobile Station (MS). First, the location server requests a Base Station (BS) to deliver location measurement data of the MS. Upon receiving a request message, the BS delivers a SCaN-ReSPonse (SCN-RSP or Advanced Air Interface (AAI)_SCN-RSP) message, the MS measures a metric indicated by the SCN-RSP (or AAI_SCN-RSP) message and delivers a measurement value to the BS by using a SCaN-REPort (SCN-REP or AAI_SCN-REP) message. Upon receiving the measurement value, the BS delivers the measurement value to the location server. The location server calculates a location of the MS by using measurement data according to a pre-defined location calculation algorithm, and delivers location information to the MS which has requested the location information.
As described above, according to a current wireless protocol, upon receiving the SCN-RSP (or AAI_SCN-RSP) message, the MS always transmits the SCN-REP (or AAI_SCN-REP) message in response thereto. Furthermore, the location server can request location measurement data of one MS up to 16 times according to a configuration of a vendor. However, upon receiving a location measurement data request, the MS can reject transmission of measurement data for reasons of protecting a user's privacy, and the like. In this case, the BS cannot know why the location measurement data is not delivered from the MS, and determines that collecting of the measurement data has failed due to a bad a wireless environment of the MS. As a result, the BS repetitively retransmits the SCN-RSP (or AAI_SCN-RSP) message. Accordingly, although the MS does not transmit the measurement data, wireless resources are wasted due to the repetitive measurement data request of the BS.
Therefore, a need exists for an apparatus and a method for avoiding an unnecessary request of measurement data required to determine a location in a broadband wireless access system.